The shipment turned up last week in the mailroom of the world body, where phony diplomatic pouches into which the drug had been stuffed attracted the staff’s attention, the head of security, Gregory Starr, said Thursday.

Authentic pouches have the words “United Nations” and “Diplomatic Mail” printed on the outside, as well as the body’s logo. But these cheap cotton bags had only the logo. There was no wording, no address, no manifest, no airway bill. They had been delivered from Mexico by the courier company DHL, according to diplomats who spoke on the condition of anonymity because they were not authorized to discuss the seizure.

When the bags were opened, the contents appeared to be 14 notebooks wrapped in cellophane, Mr. Starr said, but on further inspection they were found to be hollowed out and each one filled with a kilogram, about 2.2 pounds, of cocaine.

The contents were handed over to the Police Department and the federal Drug Enforcement Administration for further investigation. The contents did not originate from United Nations offices in Mexico, Mr. Starr said, and DHL handles official mail, he said. Nor did he think it was intended for anyone at the world body.

More likely, he said, is that someone had the idea to use the counterfeit diplomatic pouches to escape inspection at the Mexican border, and the plan went awry when they were actually delivered to the United Nations.